Water repellent treatment techniques for construction materials to date have been developed under ordinary concrete or mortar molding blend conditions and have targeted improvement in water repellency of airtight structures.
A prior patent closely related to the present disclosure on a water repellent technique for solid mortar or concrete with less porosity discloses development of an aqueous organic silicon-based composition serving as a permeable water absorption preventive material (Patent Literature 1). There has been also developed mortar or a concrete composition that is mainly made of a calcareous raw material and a siliceous raw material with adding a silicone oil, causes no deterioration in strength, and has excellent water repellency (Patent Literature 2). Prior patents on application of water repellent treatment to the surface of a sand aggregate for mortar or cement disclose use of waterproof mortar (Patent Literature 3) and a method of producing a highly strong cement hardened body (Patent Literature 4).